Disk drives offer many advantages over traditional backup media such as tape. For example, disk drives provide random access, while tape can only be accessed sequentially, making it more time consuming to access stored data from tape. Due to advantages like this, disk drives have gained popularity as backup devices, especially as disk drive prices have decreased relative to the prices of more traditional backup media. The lowered cost of disk drives has also reduced the cost of increasing the redundancy of a disk drive-based storage system (e.g., by using a redundant array of independent disks).
The increased use of disk drives, especially when used to provide increased redundancy, has led to increasing number of disk drives being included in storage arrays. This in turn has led to increased storage array power consumption. This increased power consumption can increase the expense of operating the storage array. Additionally, the increased power consumption of large numbers of disk drives can lead to thermal problems, which can in turn lead to increased failure rates within the storage array. In order to address this concern, some storage array vendors have begun implementing power management features in their storage arrays. For example, massive array of idle disk (MAID) arrays are configured so that inactive disks within the array are powered down. These types of storage arrays make it easier and more economical to operate large storage arrays, relative to similarly-sized arrays that are designed to have all disks operating at full power every hour of every day.
Unfortunately, there is currently a lack of coordination between the power management activity being implemented in a storage array and the data access patterns generated by the storage management system using that storage array. This can result in inefficiencies. For example, a data access pattern may be such that successive reads target storage devices that are currently cycled off by the storage array's power management system. To complete the reads, it may be necessary to cycle each storage device on in succession, which can in turn cause increased power consumption and/or decreased performance. As this example shows, it is desirable to further enhance power management features in storage systems in order to avoid these potential inefficiencies.